Issues with random pausing on music/video apps and sound not working on headphones

1- Random pausing:

I am experiencing pausing issues on music apps on my Android (Pandora, Spotify, YouTube Music). These issues mostly occur whenever I go for my afternoon walks/exercise, and they are a major distraction to my exercise having to check my phone every few seconds/minutes for some unexpected pausing as I'm listening to my music, with my phone placed safely in the pockets of my clothing.

I've been wondering for the longest time if the way I'm placing my phone in my pockets is causing these apps to randomly pause the music by itself without me actually touching it, but then I've reached out to the Help Center for each of the music apps (Pandora, Spotify, YouTube Music) that I've mentioned for assistance and support, and they have suggested that it most likely is an issue with the phone device itself, so I'm going to need some step-by-step assistance to troubleshoot these issues with my phone.

I've never before experienced these pausing issues with the phone, since it's a new upgraded version of my Android which I've just received for my birthday last August, so even then when I first started using it, I've never had any issues with pausing as I'm playing my music.

Before that, though, I still have my older phone with me (which I believe I've had since 2016), and even on that old phone, I've never before experienced any pausing issues with it. These issues are more so occurring on this new, current upgraded phone that I have. IF you want me to specify the names of each phone, I'd be more than glad to do so.

The pausing is never an issue when I'm playing these music apps on my PC, so I'm going to assume that it's an issue that is prominent with my mobile phone device. Since I go for my walks pretty much every day, and I like to place my phone in a safe area such as my pockets, I'm beginning to conclude that the way I place my phone in my pockets is causing the music to abruptly pause, especially since I'm wearing the USB-C headset that comes attached with this phone that I've had since last August as my birthday present.

Before this year, I've never experienced this issue before; I've gone for my walks all through last year during the pandemic and I've always placed my phone safely in my pockets of my clothes (jeans, sweaters, jackets, etc.), and NEVER ONCE have I experienced pausing issues. I'm not sure what the issue is, but I'd like to know as soon as possible so that I can't keep having these distracting issues take time and pleasure away from my daily exercise.

2- Sound issues:

The headset that comes attached to my phone is suddenly acting weird. When I wear the headphones for my walk, as I've previously stated in my issue with the music pausing of music apps, when the phone is placed in my pocket and the music randomly pauses, when I un-pause the music, the sound would unexpectedly come OUT FROM the headphones, since I'm always wearing the headphones to go walking.

This is all happening on this new phone that I currently have, since I've gotten it for my birthday last August. I've never before experienced this issue with the older phone that I've had since 2016; also, another issue with the older phone is that it would unexpectedly lose data connection whenever I step out of my house to go to the park for my walks/exercise.

So, I'm not able to use the older phone to listen to my music freely because it doesn't have any pausing issue; it's just an issue with the new phone that I'm currently in dominant use of. I'm not sure why that is, but I'd like to be able to use the old phone as well as the new phone, and I'd like for the new phone to be free of the pausing issues and sound issues with the headphones.

The headset is a little broken, but it's still usable, but if not, is there a way that I can get a new one to get it replaced so that it can work properly and the sound doesn't have to travel OUT from them?